Variable pressure fluid pump



Oct. 11, 1960 J. ZUBATY 2,955,475

VARIABLE PRESSURE FLUID PUMP Filed Jan. 10, 1957 3 Sheets-Sheet 1INVENTOR.

ATmPAEY Oct. 11, 1960 J. ZUBATY VARIABLE PRESSURE FLUID PUMP 3Sheets-Sheet 2 Filed Jan. 10, 1957 INVENTbR. By c/zigafiiw? A TTOP/VEYFiled Jan. 10, 1957 Oct. 11, 1960 J. ZUBATY 2,955,475

VARIABLE PRESSURE FLUID PUMP 3 Sheets-Sheet 3 INVENTOR.

ATTORNEY extending transversely of the pump housing.

United States Patent M .VARIABLE PRESSURE FLUID PUMP Joseph Zubaty,Flint, Mich., assignor to General Motors Corporation, Detroit, Mich., acorporation of Delaware Filed Jan. 10, 1957, Ser. No. 633,456

3 Claims. (Cl. 74-'60) The invention relates to a variable pressurefluid pump and more particularly to a pump of the wobble plate type. Thepump with the .various modifications disclosed is comprised of aplurality of plunge'rs which are reciprocated by the action of a wobbleplate and act upon either a common diaphragm or directly to produce adesired pressure in the fluid. Several arrangements for adjustment ofthe pump stroke are disclosed which provide minute adjustment.

Pumps of the type with which the invention is concerned are. adapted foruse in systems requiring a relatively constant source of fluid under apredetermined pressure. They can be accurately adjusted by adjusting thetilt angle of the wobble plate. In order to be used in high pressuresensitive systems such as automotive fuel injection systems however,pumps previously known have not obtained the high degree of accuracy ofpressure control necessary. Such pumps must have a long life and berelatively free from mechanical failures while providing the high degreeof accuracy required. The pumps herein disclosed which embody theinvention are adapted to a long trouble-free life and may be veryaccurately controlled either by pre-set mechanisms or pressurecontrolled devices which are subject to the varying conditions in theassociated equipment. The pumps may be used as fuel pumps for automotiveengines and are also adapted to other uses requiringthe features setout.

In the drawings:

Figure 1 shows a pump in cross-section and embodying the invention.

Figure 2 shows a modification of the pump pressure adjusting controlsfor the pump of Figure 1.

Figure 3,is a View taken in the direction of arrows 33 of Figure 2.

Figure 4 shows a second modification of the pump pressure adjustingcontrols for the pump of Figure 1.

Figure 5 shows a modified pump with pressure adjustingcontrols sensitiveto operating conditions of the engine and having parts broken away andin section.

Figure 6 shows another pump modification with a modified form ofmechanism for adjusting the pump pressure.

The pump shown in Figure 1 includes a housing 10 having integrallyformed therewith an end plate 12 in which a hub 14 is centrally located.Bearing 16 is mounted within hub 14 and receives drive shaft 18 therein.

Drive shaft 18 extends through the housing and into a bearing 20 whichis secured in pump end cover 22. Intermediate housing 10 and cover 22are a plurality of plates These plates include plunger guide plate 24,outlet valve and pressure chamber plate 26 and inlet valve and manifoldchamber plate 28. A plurality of bolts 30 may be used I to secure cover22 and plates 24, 26 and 28 to the housing 10. In orde'rto properlyassemble the plates in relation to the remainder of the pump, cover 22may be provided with 'an inwardly extending hub 32 on which the plates24,'26 and 28 are piloted- A key or other suitable means 76 is tiltedabout that shaft.

may be used to permit assembly of the plates only when they are inproper alignment relative to each other and to the cover 22. Bolts 34may be provided to fasten the plates to the cover in order to permitremoval and assembly of the plate and cover group as a unit. Thehousing, plates and cover are preferably separated and sealed by gasketspositioned between adjacent elements.

Cover 22 may be provided with an inlet passage 36 and an outlet passage38. Plate 28 may be provided with an annular manifold type inlet chamber40 which is preferably formed as a groove in the upper side of theplate. When the plate 28 is assembled on the cover 22, the lower surfaceof the cover closes the groove and forms the chamber. Inlet passage 36is aligned with the chamber 40. Plate 28 is also provided with anannular manifold type outlet chamber 42 which may be formed as a grooveon the lower side of the plate. Chamber 42 is concentric with and largerin diameter than chamber 40. An outlet passage 44 connects chamber 42with outlet passage 38.

Plate 26 is provided with a plurality of pressure chambers 46 and inletpassages 48 and an outlet passage 50 for each of the pressure chambers.Each of the outlet passages 50 is provided with an outlet valve 52 whichis mounted in a recess formed in the upper side of plate 26. Each of theinlet passages 48 is provided with an inlet valve 54 which is mounted inrecesses provided in the lower side of plate 28. The inlet and outletvalves may be of the check valve type.

The plunger guide plate 24 may be bored to form cylinders 56 which areadapted to receive pump plunger pistons 58. Each of the cylinders 56 arein alignment with an inlet passage 48 and an outlet passage 50 and apressure chamber 46. The diaphragm 60 is preferably made of a materialwhich operates satisfactory as a gasket between plate 24 and plate 26.Each portion of the diaphragm 60 which extends between the pressurechamber 46 and the cylinders 56 is adapted to be engaged on its lowerside by pistons 58 and on its upper side by a diaphragm return spring62. Diaphragm 60 is therefore reciprocated with a pumping action whenpistons 58 are reciprocated within cylinders 56.

Each of the pistons 58 has a plunger arm 64 extending down from itslower surface and terminating in a rounded end 66. Individual sockets 68are formed within an actuating ring 70 and are adapted to receiveplunger ends 66. Ring 70, is preferably mounted on the outer race of abearing 72 with the inner race of the bearing secured to a hub 74extending around drive shaft 18 and integrally formed with anoscillating member 76. Drive shaft 18 has an enlarged spherical gland 78formed at a position within hub 74. The gland 78 has a diameter which isgreater than the diameter of shaft 18 at this point and is substantiallyequal to the internal diameter of hub 74. This construction will permitactuating ring 70 to be tilted about the axis of drive shaft 18 whenoscillating member An enlarged section of the drive shaft 18 is formedintermediate the point at which drive shaft 18 passes through hub 14 andthe gland 78. A

an elongated hinge slot 86 to permit a slight radial movement of theoscillating member when it is tilted. A spring aperture 90 may be formedthrough driving member 82 and one or more plunger control springs 92 maybe mounted within the depression 88 and the aperture 90.

The lower end of aperture 90 may be threaded to receive a spring tensioncontrol plug 94. Plug 94 may be adjusted to impress the desired tensionon plunger control springs 92. The tension so impressed tiltsoscillating member 76 about hinge pin 84 to a desired angle. Actuatingring 70, being mounted on the outer race of bearing 72, also tilts atthe same angle to regulate the stroke of pistons 58 within cylinders 56as the drive shaft is rotated. Since hinge pin 84 may move radiallywithin slot 86, the pivot point for oscillating member 76 and actuatingring 70 is at the center of spherical gland 78.

The position of the tension control plug 94 is pre-set prior to assemblyof the plate and cover group to the pump cover and the pump will have astroke of the desired length. An access may be provided in end plate 12to permit further adjustments without disassembling the pump if desired.As the pistons 58 reciprocate within cylinders 56, diaphragm 60 isreciprocated within the pressure chamber 46. On the down stroke, fluidis drawn through inlet passage 36 and annular manifold chamber 40. Theinlet check valve 54 is opened and fluid flows through inlet passage 48to the pressure chamber. On the up stroke of the piston and diaphragm,inlet valve 54 is closed and outlet valve 52 is opened, permitting thepressurized fluid to flow through outlet passage 50 to annular manifoldchamber 42 and to be delivered to a desired point from outlet passage38.

A pin 96 may be secured to the lower side of plate 24 in order toprevent the rotation of actuating ring 70. This pin may mesh with a pairof lugs 98 which are formed on actuating ring 70. Pin 96 will thenprevent any rotary motion of actuating ring 70 in either direction.

A modification of the oscillating member adjusting mechanism is shown inFigures 2 and 3. Housing 110 is provided with an end plate 112 and anoutwardly extending hub 114 in which a bearing 116 is mounted. Driveshaft 118 is rotatably mounted within bearing 116.

The pump pistons are actuated by plunger arms 164 which are providedwith rounded ends 166 and received within sockets 168. These sockets areformed in a circumferentially spaced arrangement in the upper side of anactuating ring 170. The actuating ring 170 is mounted on the outer raceof the bearing 172. The inner race of the bearing is secured about a hub174 formed on and extending from the upper side of oscillating member176. A spherical gland 178 is formed on drive shaft 118 and ispositioned radially inward from hub 174. A drive pin 180 is provided indrive shaft 118 and is in driving engagement with driving member 182.Oscillating member 176 is secured to driving member 182 at one side byslotted hinge 184. A spring receiving depression 188 is formed in thelower side of oscillating member 176 and a spring aperture 190 extendsthrough driving member 182 and is in alignment with depression 188. Aplunger con trol spring 192 extends through aperture 190 and intodepression 188. A spring tension control arm 195 is pivoted to the lowerside of driving member 182 by hinge 131 and is provided with a springreceiving depression 133 in alignment with aperture 190. The end ofplunger control spring 192 opposite the end received in recess 188 -isreceived within depression 133. A pin 196 may be fastened to anon-rotating part of the pump and extend downwardly into a recess 199formed within actuating ring 170. Pin 196 will then prevent theactuating ring from rotating.

Spring tension control arm 195 is provided with an enlarged aperture 135through which drive shaft 118 extends. Arm 195 is also provided with adownwardly extending cam 137 on either side of aperture 135.

End plate 112 is provided with an inwardly extending hub 139 which mayhave an internal diameter approximately equal to the external diameterof the outer race of bearing 116. A thrust bearing 141 has its lowerring 143 piloted on the outer surface of hub 139 and may be rotatedrelative to that hub. A stationary cam 145 is concentric with hub 139and positioned intermediate thrust bearing 141 and the inner surface ofend plate 112.

.The upper surface of cam 145 is preferably formed as a three-prongedface cam. The lower surface of lower bearing ring 143 may also beprovided with a threepronged face cam which is complementary to the cam145. The upper ring 147 of bearing 141 has its upper surface inengagement with tension control arm cams 137 at two points substantiallyin alignment with the central axis of the drive shaft 118.

The lower ring 143 has a control lever 149 extending radially therefromto which is attached an actuating rod 151. Rod 151 may extend generallyperpendicular to and be spaced from drive shaft 118. Rod 151 passesthrough a guide bushing 153 in housing and is connected at its oppositeend to a vacuum sensitive diaphragm 155. Diaphragm 155 separates a spaceformed by cover plates 157 and 159 into a pair of chambers 16-1 and 163.Chamber 161 is subject to atmospheric pressure while chamber 163 issubject to intake manifold vacuum. A spring 129 is provided within thevacuum chamber 163 to urge actuating diaphragm 155 in a direction towardchamber 161.

When there is no vacuum impressed upon diaphragm 155, actuating rod 151has lower ring 143 positioned in a counterclockwise direction as viewedin Figure 3. Cam 145 and the cam formed on lower ring 143 permit' thrustbearing 141 to be in a position on its axial movement line nearestcontrol arm 195. As the vacuum in chamber 163 increases, actuating arm151 is moved toward vacuum chamber 163, rotating lower ring 143clockwise as seen in Figure 3. Thrust bearing 141 is permitted to moveaxially away from tension control arm 195 by means of the cam 145. Sincethe upper ring 147 of the thrust bearing is in engagement with the cams137, tension control arm 195 is pivoted downwardly about hinge 131,decreasing the tension on spring 192. This decreased tension causesoscillating member 176 to tend to pivot about slotted hinge 184,resulting in a tilting action about spherical gland 178. Actuating ringis then tilted to the same degree as oscillating member 176, decreasingthe stroke of the plungers 164. When the vacuum in chamber 163approaches atmospheric pressure due to increased speed or torquerequirements on the engine, spring 129 moves rod 151 to rotate cam 143counterclockwise, increasing the stroke of the plungers. The actuatingmechanism may be modified to use the increased vacuum force to increasethe plunger stroke length if desired.

Another modification of the oscillating member adjusting mechanism isillustrated in Figure 4. The housing 210 is provided with an end plate212 and an outwardly extending hub 214 in which a bearing 216 issecured. Drive shaft 218 is rotatably mounted within bearing 216.Housing 210 is provided in one side with an access opening 253 which isnormally plugged during operation of the pump. The plug may be removedto adjust the mechanism. The pump, which may be similar to the pump ofFigure 1, is provided with plunger arms 264 having rounded ends 266which are received within sockets 268. These sockets arecircumferentially spaced in the upper surface of the actuating ring 270.The lower surface of ring 270 is provided with an annular depression inwhich is received a bearing 272. Immediately below the actuating ring270 and in bearing engagement with bearing 272 is an oscillating member276. Both the actuating ring 270 and the oscillating member 276 extendcircumferentially around the drive shaft 218. A drive pivot pin 280extends transversely through drive shaft 218 and is received withinslots formed in the bridge portion 282 of oscillating member 276. Thisarrangement permits the oscillating member 276 to rotate about the pivot280 and to be rotatably driven by that pivot. Actuating ring 270 isprevented from rotating relative to housing 210 by pin 296. This pin issecured to the housing and received within recess 299 formed within theupper surface of ring 270.

The lower side of oscillating member 276 is provided with a dependinglug 289 which threadably receives an adjusting screw 294. Screw 294extends radially towards drive shaft 218 and is in engagement with theouter surface of that shaft intermediate drive pivot 280 and hearing216. A lock nut 291 may be provided to lock the adjusting screw 294 inthe desired position relative to lug 289. Adjusting screw 294 may bescrewed inwardly or outwardly to arcuately position lug 289 relative todrive shaft 218. Since lug 289 is attached to the oscillating member276, the adjustment obtained through screw 294 tilts member 276 to thedesired angle. Actuating ring 270 is also tilted to the same degree,adjusting the stroke of the plunger arms 264 to obtain the desiredpressure. A modified pump and adjusting mechanism is shown in Figure 5.The pump has the actuating pistons concentrically disposed in relationto the manual tilt adjusting mechanism. The actuating ring is rigidlyattached to a vacuum sensitive diaphragm which provides the vacuumsensitive adjustment of the stroke of the pump pistons.

The pump of Figure 5 includes a housing 310 with which a web 312 isintegrally formed. A bearing hub 314 is located centrally within web312. A bearing 316 is received within hub 314 and provides a rotatablemount and end locating point for the end of drive shaft 318. A pumpcover 322 is provided through which drive shaft 318 extends and bearing320 is located in the pump cover 322 to provide a rotatable mount forthe drive shaft. Intermediate the housing 310 and the pump cover 322 areseveral stacked plates which may be separated by gaskets. These platesinclude the plunger guide plate 324, the pressure chamber plate 326 andthe valve plate 328. Pump cover 322 may have an inwardly extending hub332 on which plates 324, 326, and 328 are piloted. An inlet passage 336may be provided in pump cover 322 to enable the fluid being pumped toenter. An outlet access passage 338 may also be provided in pump cover322 for delivery of the fluid from the pump. Pump cover 322 has formedwithin its upper surface an annular inlet manifold chamber 340.Individual'outlet manifold chambers 342 may be provided concentricallyoutward from inlet manifold chamber 340. Outlet passages 344 connecteach of the pressure chambers 346 with an outlet manifold chamber 342.Inlet passages 348 connect each of the pressure chambers 346 with inletmanifold chamber 340.

Inlet valve 354, which may be of the check valve type, is

mounted in between inlet passage 348 and manifold chamber 340 and may belocated within plate 328. Outlet valve 352, which may also be of thecheck valve type, is located between outlet passage 350 and outletpassage 344 and occupies a recess provided in plate 328. Plate 324 has aplurality of cylinders 356 formed therein which are complementary topressure chambers 346 in plates 326. Cylinders 356 and chambers 346 areseparated by a pump diaphragm 360 which is mounted between plates 324and 326. The diaphragm acts as a gasket between these plates and theportions of the diaphragm which are exposed to the pressure chambers 346act as pump diaphragms. Pump plunger pistons 358 are reciprocablyreceived within cylinders 356 and engage diaphragm 360 at their outerends. A diaphragm return spring 362 may be provided in each of thepressure chambers 346. Pistons 358 may be integrally formed with plungerarms 364 which terminate at their ends opposite the pistons in roundedends 366. Sockets 368 are formed Within actuating rings 370 and receivethe ends 366 of the plunger arms. Actuating ring 370 is preferablymounted on the outer race of the bearing 372. The inner race of bearing372 is secured to hub 374 which extends around and is radially spacedfrom drive shaft 18. Hub 374 is integrally formed with an oscillatingmember 376. At a point within hub 374 drive shaft 318 is provided withan enlarged spherical gland 378 which has a diameter substantially equalwith the diameter of oversizedhub passage 375. Actuating ring 370 may betilted about the axis of drive shaft 18 by arcuate movement of hub 374about gland 378.

An enlarged section of the drive shaft has a drive pin 380 extendingtransversely therethrough at a point inter mediate the place where driveshaft 318 passes through hub 332 and the position of gland 378. Drivingmember 382 may be press fitted on drive shaft 318 and secured thereto bydrive pin 380. Oscillating member 376 is hinged at one side of drivingmember 382 by means of a slidable hinge 384. Driving member 382 isprovided with a hinge slot 386 which permits hinge 384 to slide radiallywhen the oscillating member is tilted. Actuating ring 370 may beprevented from rotational movement with respect to housing 319 by pin396 which extends downwardly from web 312 and engages ring 370 in recess392.

An initial manual adjustment of the oscillating member 376 may be madeby screwing tapered adjusting screw 393 inwardly or outwardly in thethreaded depending lug attached to the lower side of member 376. Thetapered end of screw 393 may contact bevel surface 391 which is formedon the side of driving member 382 adjacent screw 393. When screw 393 ismoved inwardly, the angle between oscillating member 376 and drivemember 382 is increased.

The pump of Figure 5 may be controlled during engine operation by intakemanifold vacuum. A vacuum sensitive diaphragm 355 is provided for thispurpose. Cover plate 359 may be suitably secured to pump housing 310 sothat web 312 and the cover plate form a space divided by diaphragm 355to define atmospheric chamber 361 and vacuum chamber 363. One or moresprings 329 may be mounted between cover 359 and diaphragm 355 to resistmovement of the diaphragm when vacuum is increased therein and to returnthe diaphragm to its neutral position when the vacuum approachesatmospheric pressure. The springs 329 may be adjusted by an adjustableSpring retainer 323 which may be threaded into the cover plate 359. Astroke limiting screw 321 may be threaded through retainer 323 toprovide a maximum stroke limiting position for diaphragm 355. Controlarm 351 may be rigidly attached to diaphragm 355 and extend in agenerally perpendicular direction from the diaphragm. The opposite endof arm 351 may be threaded into or otherwise attached to actuating ring370. A bellows seal 353 may be secured in the aperture in web 312through which arm 351 extends. Seal 353 allows longitudinal movement ofarm 351 while effectively sealing atmospheric chamber 361 from theinterior of the pump. When diaphragm 355 is moved under the influence ofincreased vacuum in chamber 363, arm 351 is moved in a directiongenerally parallel to drive shaft 318 and actuating ring 370 is pivotedabout spherical gland 378. The tilt of ring 370 therefore depends uponthe speed and torque requirements of the engine which are sensed byengine intake manifold vacuum.

The modified pump and adjusting mechanism shown in Figure 6 does notrequire the use of a pump diaphragm nor a vacuum control system. Thepump housing 410 includes an end plate 412 in which an outwardlyextending hub 414 is formed to receive bearing 416. Drive shaft 418extends through hub 414 and is rotatably supported by hearing 416. Theother end of drive shaft 418 is supported in bearing 420 which issecured in a depression formed in pump cover 422. Cover 422 may besecured to pump housing 410 by any suitable means such as bolts 430. Aplunger guide plate 424, an inlet valve and pressure chamber plate 426and an outlet valve and manifold chamber plate 428 are positionedbetween cover 422 and housing 410. Bolts 434 may be provided to secureplates 424 and 426 to plate 428. Plate 428 is provided with an inwardlyextending hub 432 on which plates 424 and 426 are piloted.

Cover 4 22 may have an inlet access passage 436 and an outlet accesspassage '438 formed therein. Plate 428 may have an annular inletmanifold chamber 440 formed in its upper side and an annular outletmanifold chamber formed in its lower side. These chambers are preferablyconcentric with the axis of plate 428 and of different dimeters. Anoutlet passage 444 may connect passage 438 with chamber 442. Inletpassage 448 may be formed in plate 428 and connect chamber 440 with thepump pressure chambers 446. An inlet valve 454 may be located within thepressure chamber 446 adjacent passage 448. An outlet passage 450 may beprovided in plate 426 to connect chamber 442 with pressure chamber 446and may be controlled by an outlet valve 452. Plate 424 may have aplurality of bosses extending downwardly therefrom in which pumpcylinders 456 are formed. A pump plunger piston 458 may be mounted forreciprooable movement within each of the chambers 456. A piston ring 461may be provided to seal the pressure chambers from the interior of thepump housing. A piston return spring 462 may abut plate 424 and surroundthe bosses through which cylinders 456 :are formed. The other end ofsprings 462 may abut the upper side of enlarged arcuate contacting ends466 of the pump plunger 458. The arcuate sunface of ends 466 are inengagement with actuating ring 470 and are reciprocated by the wobbleplate movement of that ring. Ring 470 is secured to the outer race ofbearing 472. The inner race of that bearing is secured to hub 474 whichis formed on oscillating member 476. A spherical gland 478 is formed onshaft 418 and is of sufiicient diameter to engage the internal surfaceof hub 474. The enlarged diameter of this gland permits oscillatingmovement of member 476. Drive shaft 418 is provided with a transverselyextending drive pin 480 at a point intermediate gland 478 and bearing 416. A drive member 482 is mounted for pivotal movement on this pin andis driven rotatably by the pin when drive shaft 418 is rotated.Oscillating member 476 is pivoted to one side of drive member "482 byslidable hinge 484. The upper surface of drive member 482 which isopposite hinge 484 may be provided with a flat surface 491 and athreaded lug 492 adjacent the flat surface and generally perpendicularthereto. A difierential thread adjusting screw 495 may be threaded inthe lug "492 and terminate in an adjusting wedge 493. The upper surfaceof wedge 493 may be beveled and be complementary to the bevel surface489 formed on oscillating member 476. When adjusting screw 495 isturned, web 493 moves radially inward or outward to increase or decreasethe angle formed between drive member 48 2 and oscillating member 476.The change .in this angle causes a commensurate change in the tilt angleof actuating ring 470. The strokes of the pistons 458 are adjusted bychanging the tilt angle of ring 470 to adjust the output pressure of thepump. Actuating ring 470 is prevented from rotation relative to housing410 by a pin 4% which is attached to the housing. Pin 496 extendsinwardly to engage a pair of lugs 498 which are formed on the upper sideof ring 470.

The pumps and pump stroke adjusting mechanisms which are the subject ofthe invention provide for a constant delivery of a fluid under apredetermined pressure which may be preset or controlled by operatingconditions of associated mechanisms such as an internal combustionengine.

What is claimed is:

l. A vacuum controlled variable pressure pump having a tiltableactuating ring and reciprocable pistons driven by said ring, a chamberformed in one end of said pump and having a diaphragm extending therethrough, one side of said diaphragm being sensitive to vacuum induced bya vacuum source, an arm rigidly secured to said diaphragm and to saidtiltable actuating ring whereby said actuating ring is tilted bymovement of said diaphragm when said vacuum is modified, said tiltableactuating ring having a manually adjustable tilt control for initiallyadjusting the tilt of said actuating ring, said tilt control including atapered adjusting screw and a beveled driving member cooperating withsaid screw to introduce a tilt angle to said actuating ring.

2. The mechanism of claim 1, said pistons being concentrically spacedabout said manually adjustable tilt control.

3. A differential pressure controlled variable pressure pump having atiltable actuating ring and reciprocable pistons driven by said ring, achamber formed in one end of said pump and having a diaphragm extendingtherethrough, one side of said diaphragm being sensitive to a pressureinduced by a pressure source, an arm rigidly secured to said diaphragmand to said tiltable actuating ring whereby said actuating ring istilted by movement of said diaphragm when said pressure is modified,said tiltable actuating ring having a manually adjustable tilt controlfor initially adjusting the tilt of said actuating ring, said tiltcontrol including a tapered adjusting screw and a beveled driving membercooperating with said screw to introduce a tilt angle to said actuatingring.

References Cited in the file of this patent UNITED STATES PATENTS2,040,390 Loe May 12, 1936 2,146,117 Gros Feb. 7, 1939 2,256,079 DinzlSept. 16, 1941 2,392,279 Woods Ian. 1, 1946 2,513,758 Talbot July 4,1950 2,577,675 Burkland Dec. 4, 1951 2,765,751 Osius Oct. 9, 19562,860,517 Clauble Nov. 18, 1958 FOREIGN PATENTS 21,319/29 Australia July19, 1930

